Where to find Font libraries from previous versions?

I began using corel at version 4, and then spent years using version 8.  I recently upgraded from x4, which I used extensively as wel.  During this time, I've updated to windows 10, as well.  Now that I have x8, I'm running into a huge number of problems regarding fonts.

First off, nearly every file I've ever created has fonts not included with x8.

1. How different are the font libraries included with the various versions?
2. Why can't Corel assign suitable replacements to suggest when it finds a font it previously shipped with, and has not included with the current release?

When I try to install the fonts from previous versions, Windows 10 doesn't allow it, as it says it is incompatible with the installer program.

1. Are there inline libraries of these previously shipped font libraries, to allow registered users to download them directly, bypassing Windows compatibility issues?
2. If not, is there some setting within the Font Manager or an internal method of automatically finding these fonts as the program encounters them within files?

I'd appreciate any help as this issue has nearly crippled my productivity, and is affecting my business daily.  As soon as I upgraded, my output ground to a halt.